#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>
#include <assert.h>
#include <sys/mman.h>

#define STRING_MAX 32

struct etudiant {
  int id;
  char nom[STRING_MAX];
};

struct cours {
  int id;
  char nom[STRING_MAX];
};

struct note {
  int etudiant_id;
  int cours_id;
  int note;
};

struct cours *cours = NULL;
int nb_cours = 0;

void add_etudiant(char* name) {
  int fd = open("etudiants.dat", O_RDWR);
  int file_size=lseek(fd, 0, SEEK_END);
  int nb_etudiants = file_size/sizeof(struct etudiant);

  struct etudiant e;
  e.id = nb_etudiants;
  strncpy(e.nom, name, STRING_MAX);
  write(fd, &e, sizeof(struct etudiant));
  close(fd);
}


void add_cours(char* name) {
  int fd = open("cours.dat", O_RDWR);
  int file_size=lseek(fd, 0, SEEK_END);
  int nb_cours = file_size/sizeof(struct etudiant);

  struct cours c;
  c.id = nb_cours;
  strncpy(c.nom, name, STRING_MAX);
  write(fd, &c, sizeof(struct cours));
  close(fd);
}

void add_note(int etudiant_id, int cours_id, int note) {
  int fd = open("notes.dat", O_RDWR);
  struct note n;
  n.etudiant_id = etudiant_id;
  n.cours_id = cours_id;
  n.note = note;
  write(fd, &n, sizeof(struct note));
  close(fd);
}

void print_note(struct etudiant *e, struct note *n) {
  struct cours *c = &cours[n->cours_id];
  assert(c->id == n->cours_id);

  printf("\t%s\t%d\n", c->nom, n->note);  
}

void print_bulletin(struct etudiant *e) {
  int fd = open("notes.dat", O_RDONLY);
  if(fd < 0) {
    perror("Cannot to open etudiants.dat");
    abort();
  }

  struct note n;
  while(read(fd, &n, sizeof(n))>0) {
    if(n.etudiant_id == e->id) {
      print_note(e, &n);
    }
  }
  close(fd);
}

void print_bulletins() {
  int fd = open("etudiants.dat", O_RDONLY);
  if(fd < 0) {
    perror("Cannot to open etudiants.dat");
    abort();
  }
  
  struct etudiant e;
  while(read(fd, &e, sizeof(e))>0) {
    printf("%d - %s\n", e.id, e.nom);
    print_bulletin(&e);
  }
  close(fd);
}

int main(int argc, char**argv) {

  int fd = open("cours.dat", O_RDONLY);
  if(fd < 0) {
    perror("Cannot to open etudiants.dat");
    abort();
  }

  struct stat stat;
  if(fstat(fd, &stat) < 0) {
    perror("fstat failed");
    abort();
  }
  nb_cours = stat.st_size / sizeof(struct cours);

  cours = mmap(NULL, stat.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
  if(cours == MAP_FAILED) {
    perror("mmap failed");
    abort();
  }
    
  print_bulletins();

  munmap(cours, stat.st_size);
  close(fd);
  return EXIT_SUCCESS;
}